Reasons Spam Email Is Getting Past Your Anti-Spam Filter

Spam email has always been a huge problem. It clutters up your inbox, making it hard to find the emails important to you. With an anti-spam service, filters work to combat the vast majority of spam from flooding your inbox. However, sometimes you may see an unexpected increase in the amount of spam delivered to your inbox, even with an active anti-spam filter. So, why does this ebb and flow of spam happen? A spam filter scans all email against a large list of criteria and assigns it a spam score.

Here is some of the criteria used to analyze emails.

Where does the message originate? Is it a trusted IP address and sender domain?

What content does the email contain? Are their any spam keywords?

What are the quality and safety of links within the email?

Has the subscriber flagged the email as spam in the past?

Has the email been opened, if so, how many times?

How long has the email been opened for review?

Does the subscriber enable images?

What is the originators’ relationship to the subscriber?

The list of factors continues to grow as the filters use subscriber engagement to better identify spam against an email the subscriber wants to receive. Since spamming is such a lucrative business, spam originators are constantly seeking ways to defeat spam filters. Attackers will use tools to analyze message deliverability and modify message content until it bypasses the filter without raising any red flags. So, when a spam email is the first of its kind, the filter does not see it as a spam email, thus the spam makes it way to your account. As you mark these emails as spam or do not engage with them, the spam filter takes notice and updates as needed.

While the filter is constantly learning and managing these new attacks, another way to handle email spam is to lower the threshold the filter uses to consider a message spam. The standard setting for spam filters is a 4, but can be lowered. However, by lowering the threshold the filter may mistakenly classify legitimate messages as spam.